Biology subjects

Cauvin, A.

Publications and source records attributed to Cauvin, A..

3 recordsLinked to original sources

bioRxiv2026

Baseline microbiomes of the pillar coral Dendrogyra cylindrus reveal novel taxa and regional differences

The pillar coral Dendrogyra cylindrus is a rare but iconic member of Caribbean reefs that has suffered range-wide losses. D. cylindrus is highly susceptible to stony coral tissue loss disease (SCTLD), and the outbreak has contributed to the functional extinction of Floridas population of pillar corals. The coral microbiome can impact the health and disease resistance of coral colonies, yet little is known about what constitutes the core microbiome of D. cylindrus. This information is crucial for comparisons of healthy and diseased tissue in pathogen identification studies and can be applied to restoration efforts as a coral health metric. Therefore, we characterized the microbiomes of D. cylindrus colonies ahead of the SCTLD disease front in Belize and Curacao. The most prevalent members of the D. cylindrus microbial community were bacteria for which taxonomy could not be assigned confidently beyond the level of domain as well as the putatively endosymbiotic genera Endozoicomonas, Ca. Amoebophilus, and Spiroplasma. The coral reefs of Belize and Curacao represent distinct Caribbean marine ecoregions, and we documented regional differences in strains among predominant bacterial taxa. The understudied microbiome of D. cylindrus harbors unique bacterial lineages that are in danger of extinction along with its critically endangered coral host, and these bacterial lineages may be important bioindicators during restoration efforts. IMPORTANCETropical corals face global extinction if average temperatures rise by 2{degrees}C (3.6{degrees}F), which may occur as soon as 2050. Included in the loss of charismatic macrofauna like the majestic pillar coral is the loss of the biological and genetic diversity of its symbionts. Here we examined the bacterial and archaeal communities associated with Caribbean pillar corals and found that the microbiome was dominated by taxonomically unclassified and putatively endosymbiotic taxa. Endosymbiotic bacteria, which live inside the coral tissue, are likely to have evolved unique adaptations to become symbionts and may be important to the health and success of pillar corals in ecosystem restoration efforts.

microbiology↗

bioRxiv2025

Multidisciplinary assessments of a potentially novel acute tissue loss disease on Florida Orbicella corals

Coral disease outbreaks are an increasingly common threat to reefs. While coral disease research is expanding rapidly, there are still monumental challenges in diagnosing and differentiating among the different diseases on a reef. We used a collaborative multidisciplinary approach to characterize a potentially novel disease affecting Orbicella faveolata colonies in the Florida Keys. We tagged and fate-tracked individual lesions for progression and cessation rates, reanalyzed in situ photographs of previously monitored corals to determine prevalence and seasonality, and assessed the efficacy of amoxicillin treatments. Samples collected from lesions as well as unaffected and healthy controls were used to examine microbiomes, assess nine coral pathological parameters via histology, and measure 19 symbiont-specific physiological metrics using transmission electron microscopy (TEM). Across all analyses, we concluded that the observed disease is unlikely to be SCTLD. Many, but not all, metrics had similarities to previous descriptions of white plague, and so we additionally conducted preliminary histology on presumed white plague samples of O. franksi for comparison. However, the dearth of quantifiable histology and TEM studies on white plague did not allow us to conclusively confirm or refute comparisons to white plague. Using the recommended coral disease nomenclature, we define this specific outbreak as "Orbicella acute tissue loss disease" (OATLD). We provide unprecedented, quantified descriptions across numerous metrics of both diseased and control colonies. We suggest that these data lay the groundwork for future efforts on this disease as well as a comprehensive set of parameters against which other diseases can be compared.

physiology↗

bioRxiv2024

Two methodologies and timescales show no promotion of antibiotic resistance from in-water coral disease treatments

The decimation of reefs caused by stony coral tissue loss disease prompted the use of a topical amoxicillin treatment to prevent coral mortality. Application of this treatment led to concerns about unintentional impacts such as potential alteration of the coral microbiome and possible spread of antibiotic resistance. We used two different methodologies - microbial RNA sequencing and microbial qPCR array - to assess these concerns and to establish a baseline of antimicrobial resistance genes in coral microbes. RNA sequencing was conducted on coral mucus samples collected before and 24 hours after amoxicillin application on wild Montastraea cavernosa. While diverse antibiotic resistance genes (ARGs) were expressed, no differences were detected in ARG expression after amoxicillin treatment. Additionally, there were no notable changes in the microbial communities between the before and after samples. Microbial qPCR array was used to assess differences in ARGs over longer timescales in wild Colpophyllia natans, comparing never-treated corals with ones treated a single time seven months prior and with those treated multiple times seven months and more prior. No clinically relevant ARGs represented in the arrays were detected across any samples. A small number of above-detection reads (4 in the never-treated corals, 2 in the once-treated corals, and 0 in the multi-treated corals) may indicate weak amplification of similar environmental (non-anthropogenic) ARGs in the corals. Results indicate that the localized topical application of amoxicillin to prevent mortality of SCTLD-affected corals is neither immediately disrupting the microbiome of treated corals at the colony level nor driving the development of ARGs over immediate or longer-term time scales.

microbiology↗